The IQGAP1 N-Terminus Forms Dimers, and the Dimer Interface Is Required for Binding F-Actin and Calcium-Bound Calmodulin.

ABSTRACT: IQGAP1 is a multidomain scaffold protein involved in many cellular processes. We have determined the crystal structure of an N-terminal fragment spanning residues 1-191 (CHDF hereafter) that contains the entire calponin homology domain. The structure of the CHDF is very similar to those of other type 3 calponin homology domains like those from calponin, Vav, and the yeast IQGAP1 ortholog Rng2. However, in the crystal, two CHDF molecules form a "head-to-head" or parallel dimer through mostly hydrophobic interactions. Binding experiments indicate that the CHDF binds to both F-actin and Ca²⁺/calmodulin, but binding is mutually exclusive. On the basis of the structure, two dimer interface substitutions were introduced. While CHDFL157D disrupts the dimer in gel filtration experiments

SUBMITTER: Liu J 

PROVIDER: S-EPMC5543714 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature